If you want a litmus question to divide the Catholic Left from the Right, ask them who they blame for the paedophile priest scandals. The Right will say that it was gay priests; the left that it was the imposition of an unnatural celibacy. Underlying this is the great question of how the Church should accommodate itself to the modern understanding of sexuality, which is also our understanding of the person. Conservatives think of homosexuality as an intrinsic moral disorder; liberals mostly think the same of celibacy. Of course, Catholics in the centre say that celibacy can be made to work for some men, whatever their sexual orientation. Bishops have to say that, for they have to make the system work; and, as bishops, they are the heirs to the men who broke it and made the crisis by protecting criminal priests.

Now there is a little research to give comfort to all sides. The American Catholic bishops conference commissioned criminologists from John Jay College of Criminal Justice in Manhattan to investigate the abuse crisis as they would investigate any other crime wave, and the preliminary results were presented to them last week.

There is no question but that most of the known victims of abuse were boys, not girls: the ratio was about 80:20. This is the figure used by right-wing catholics to suggest that the problem was priests who were attracted to boys. But the two researchers who talked to the conference about their findings suggested that this was less a matter of attraction than availability.

"It's important to separate the sexual identity and the behaviour," said the lead researcher. Karen Terry: "Someone can commit sexual acts that might be of a homosexual nature but not have a homosexual identity." Her assistant, Margaret Smith, used the analogy of prison populations where homosexual behaviour is common among men who would, if they could get them, prefer women. She might also have mentioned traditional English boarding schools.

This isn't just theoretical. If Smith and Terry are right, then homosexual candidates for the priesthood are not for that reason more likely to abuse their parishioners than straight ones and this would influence recruitment policies and so the future make up of the American church. Despite convincing evidence that the priesthood there is already an extremely gay profession, openly gay candidates are presently barred even if celibate.

Their explanation for the story, as it emerges from press and blog reports, is tied up with the particular strains on American society as the repression of the Fifties gave way to the libertinism of the Seventies. Within the Catholic church, these strains were both heightened and symbolised by the reforms of the Second Vatican Council, which tried to break down the walls between church and society. One consequence was a huge exodus of men from the priesthood to get married. Another seems to have been exploitative sexual behaviour on the part of some who remained. Very little of this was paedophilia in the strictest sense: 1% of reported or discovered abuse was of children under ten. Nor can many of the abusers have had numerous victims: the best available figures are that in fifty years, around 4,400 priests abused around 6,700 victims. This is about 4% of all the Catholic priests in the USA in that period.

This is bad. It is particularly bad because the priesthood is meant to be a caring profession. Whether it is worse than the rate of abuse in secular bodies, I don't know and I suspect that no one else does either. Stories of institutionalised abuse have emerged from the Australian and Swedish child care systems this year, and I don't suppose our own now is very much better. One of the undertones of the baby P story was that social workers regarded taking a child into care as worse than amost all the alternatives. Few people feel or argue that this discredits the whole enterprise of the welfare state.

In Ireland, that the Christian Brothers have settled £145m on their victims just in advance of a report which names four successive archbishops of Dublin who were active in the coverup. The Irish scandals expose another kind of Catholic child abuse, in which the state was much more complicit than in Americas. It matters, too, that the Brothers were not priests. They had taken vows of celibacy but they cannot have had the romantic attitude to this which must have helped some priests at least to resist some temptations.

When the history of all this is written, we will discover that there was not one pattern of abuse but many, varying between countries and cultures. In all of them, though, Children whom no one wants or knows how to deal with were vulnerable to exploitation; some will always be exploited no matter how idealistic the system under which they are cared for. What matters is that the perpetrators be caught and punished: it follows what really, rightly, damaged the Catholic church was the protection of the criminals by bishops and archbishops. The reports now being drawn up are some small atonement for that.